Description: drivers: net: slip: fix NPD bug in sl_tx_timeout()
References:
 https://bugzilla.redhat.com/show_bug.cgi?id=2144379
Notes:
Bugs:
upstream: released (5.18-rc2) [ec4eb8a86ade4d22633e1da2a7d85a846b7d1798]
5.10-upstream-stable: released (5.10.112) [ca24c5e8f0ac3d43ec0cff29e1c861be73aff165]
4.19-upstream-stable: released (4.19.239) [753b9d220a7d36dac70e7c6d05492d10d6f9dd36]
sid: released (5.17.6-1)
5.10-bullseye-security: released (5.10.113-1)
4.19-buster-security: released (4.19.249-1)